temperature control

[willist2]

I'm reading an analogue input from a thermistor/resistor representing temperature increase. I would like to set limits on this to swicth on a fan when it's too hot, and the heater when it's too cold. This can be done by writing bit 7 for the fan and bit 5 for the heater to a DAQ 6008. I've tried to use analogue triggering, and also a series of logic/comparrison functions. What would be the best way to do this?

[NIquist]

Search the NI example finder for "PWM" (Pulse Width Modulation)  and "PID" (Proportional, Integration, Derivitive) to get some good ideas on the various methods for controlling analog systems including temperature.  Whether your fans and heaters are variable input or On/Off devices will determine the most appropriate methods.